There is a direct bus from AK to EPCOT. All parks have a direct bus, but for travel to and from MK, you must go to the TTC. They are building more bus stops at MK to eliminate the ned to go to the TTC, but I dont know when those will be done. Robo has a good transportation post. You might try an advanced search to find it.
ETA: Here it is...
http://www.htp.disboards.com/showpost.php?p=48903798&postcount=20
Thanks. it's been 4 years and for the life on me I couldn't remember if you could take the bus from park to park.